Harvard College Observatory (HCO)
Harvard College Observatory (HCO) is the astronomical observatory of Harvard College at Cambridge, Massachusetts; it was founded in 1839. The Observatory carries out a broad program of research in astronomy and astrophysics and includes among its instruments the 0.38-meter (15-inch) "Great Refractor," installed in 1847, which for 20 years was the largest telescope in the United States. HCO is a partner in the Magellan Telescopes project and owns telescopes at Oak Ridge, Massachusetts, that are operated by the Smithsonian Astrophysical Observatory (SAO). Since 1973, HCO and SAO have jointly run the Harvard-Smithsonian Center for Astrophysics.